KATRIN (Karlsruhe Tritium Neutrino Experiment) aims to measure the neutrino mass by analyzing the endpoint region of a Tritium spectrum using a high-luminosity source and a high-resolution MAC-E filter technique. KATRIN holds the current best limit on the neutrino mass of 0.8 eV, coming from the joint analysis of the first two measurement campaigns.
After KATRIN’s data taking, a detector upgrade, called TRISTAN, is planned. The choice for this new detector is a matrix of Silicon Drift Detectors (SDDs) made of 9 modules with 166 pixels each.
SDDs, able to sustain a high count rate, will allow a high-statistics measurement of the whole Tritium spectrum, and thus the search for new physics, like sterile neutrinos with mass in the keV-range, candidates to be Dark Matter particles.
A model for the measured Tritium spectrum is therefore needed. In this work, I will present the status of such a model, together with experimental tests of one of its parts, the detector response.